Self-priming pump

ABSTRACT

The present invention relates to a self-priming pump capable of preventing a swirl flow from developing during the self-priming operation and assuring the smooth flow of a stream of water during the pumping operation.  
     The self-priming pump has a main line ( 12 ) formed with a swirl flow forming space ( 15 ) allowing self-primed water accumulated in a casing ( 1 ) to be discharged together with air from a small scroll casing  11  through an auxiliary line ( 14 ) to the main line ( 12 ) during the self-priming operation to produce a swirl flow in the main line so as to allow air-water separation. The self-priming pump is provided with a plate member ( 16 ) for eliminating the swirl flow in the main line below the swirl flow forming space extendedly in the extension direction of the main line.

TECHNICAL FIELD

[0001] The present invention relates to a self-priming pump used forpumping.

BACKGROUND ART

[0002] Conventionally, there are known self-priming pumps described inJapanese Patent Publication No. S50-21682 and Japanese Utility ModelRegistration No. S51-47602.

[0003] The former self-priming pump comprises a large scroll casing anda small scroll casing formed around an impeller, a main line extendingfrom the large scroll casing, an auxiliary line extending from the smallscroll casing, and a casing in which an upper end of the auxiliary lineis spirally brought into communication with the main line along a wallsurface of the main line from a tangent direction thereof. The main lineis formed with a swirl flow forming space in which self-primed wateraccumulated in the casing is discharged into the main line from thesmall scroll casing through the auxiliary line together with air duringself-priming operation, thereby generating a swirl flow in the main lineto carry out air-water separation. A mushroom-like lump is provided inthe main line below the swirl flow forming space as means foreliminating the swirl flow.

[0004] In the latter self-priming pump, a bag-like liquid stagnationcasing is provided in an intermediate portion of a trap which is incommunication with a suction opening of the casing.

[0005] In the self-priming pump, swirl flow is generated in the swirlflow forming space during the self-priming operation to generatecentrifugal separation, and the air-water separation is carried outusing the centrifugal separation. At that time, there is generated acirculation flow in which self-primed liquid interflows into the mainline from the small scroll casing through the auxiliary line, andreturns into the large scroll casing from the main line and again flowsinto the auxiliary line from the small scroll casing. With thecirculation flow, the swirl flow develops like tornado. If the swirlflow develops such as to extend downward, bubble again returns into thelarge scroll casing, which hinders the self-priming operation and thus,it is necessary to prevent this.

[0006] However, if the mushroom-like lump is provided below the swirlflow forming space as in the conventional pump (former pump), there is aproblem that although the swirl flow is prevented from developing by themushroom-like lump during the self-priming operation, this mushroom-likelump hinders the water flow during the pumping operation, and since across-sectional area of the portion where the mushroom-like lump isprovided and a cross-sectional area of a portion where the mushroom-likelump is terminated (swirl flow forming space) are largely different, thewater flow is disturbed and the pumping performance becomes unstable.

[0007] Further, since air is discharged from a suction pipe whilecirculating the self-primed liquid in the casing, it is necessary toaccumulate the self-primed liquid in the casing without fail.

[0008] However, if the bag-like liquid stagnation casing is provided inthe intermediate portion of the trap which is in communication with thesuction opening of the casing as in the conventional pump (latter pump),although the bag-like liquid stagnation casing is provided, since theentire bag-like liquid stagnation casing is the straight pipe-like trap,its entire length becomes long, and the suction-side structure can notbe made compact.

[0009] Further, since the trap has the straight pipe-like shape,siphonage is prone to be generated, water (liquid) flows backward fromthe casing into the suction pipe by the siphonage, and the self-primedliquid can not be accumulated. To prevent this, it is necessary tolargely set a vertical level difference such that a trap inlet port isset higher than a trap outlet port. As a result, a pumping load isincreased, the self-priming time is increased, and the pumping abilitymust be enhanced.

[0010] The present invention has been accomplished to solve the aboveconventional problems, and it is a first object to provide aself-priming pump capable of preventing a swirl flow from developingduring the self-priming operation and assuring the smooth flow of astream of water during the pumping operation.

[0011] It is a second object of the invention to provide a self-primingpump capable of making the suction side structure compact, reducing apumping load and reducing the self-priming time without increasing thepumping ability, and capable of reliably accumulating self-primed liquidin a casing when the pump is stopped.

DISCLOSURE OF THE INVENTION

[0012] To solve the first object, the present invention (claim 1)provides a self-priming pump comprising a casing in which a large scrollcasing and a small scroll casing are formed around an impeller, a mainline extends from the large scroll casing, and a spout is formed on anupper end of the main line, an auxiliary line extends from the smallscroll casing, and an upper end of the auxiliary line is spirallybrought into communication with the main line along a wall surface ofthe main line from a tangent direction thereof, a swirl flow formingspace being formed in the main line, and in the swirl flow formingspace, self-primed water accumulated in the casing being discharged intothe main line together with air from the small scroll casing through theauxiliary line during self-priming operation, thereby generating swirlflow in the main line, and air-water separation being carried out,wherein

[0013] a plate member for eliminating the swirl flow extends in anextension direction of the main line in the main line below the swirlflow forming space.

[0014] This self-priming pump is characterized in that the swirl flowforming space is provided below the plate member as means foreliminating the swirl flow during the self-priming operation.

[0015] If the plate member is provided below the swirl flow formingspace, when the swirl flow generated in the swirl flow forming spacetries to extend downward, the swirl flow can be obstructed by a surfaceof the plate member, and it is possible to eliminate the swirl flowwhich tries to extend downward.

[0016] Further, since the plate member extends in the extensiondirection of the main line, the plate member does not hinder the waterflow during the pumping operation. Only a cross-sectional areacorresponding to a plate thickness of the plate member is varied betweena portion where the plate member is provided and a portion where theplate member is terminated (swirl flow forming space) and therefore,water flow is not disturbed, and pumping performance does not becomeunstable.

[0017] To solve the second object, the present invention (claim 2)provide a self-priming pump wherein a water tank for self-primed wateris provided between the suction opening and a suction pipe, the watertank comprises a reserving portion swelling in the lateral direction andhaving a cross-sectional area greater than an opening area of thesuction opening, a water outlet which laterally opens into a bottom endof the reserving portion and which is in communication with the suctionopening substantially horizontally, and a water inlet which laterallyopens into an upper end of the reserving portion and which is incommunication with the suction pipe, and a lower end level of the waterinlet is formed higher than an upper end level of the water outlet.

[0018] In this self-priming pump, since the reserving portion of thewater tank is allowed to swell in the lateral direction, necessaryself-primed liquid can be accumulated only by this reserving portion andthus, it is possible to reliably accumulate the self-primed liquid inthe casing 1 when the pump is stopped.

[0019] Since it is possible to reliably accumulate the necessaryself-primed liquid only by the reserving portion, the entire length ofthe pump need not be increased unlike the conventional straight pipelike pump, and it is unnecessary to largely set a vertical leveldifference between the inflow port and the outflow port. Therefore, thesuction side structure can be made compact, and a pumping load can bereduced. Thus, it is possible to reduce the self-priming time withoutincreasing the pump ability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is an axial sectional view showing an essential portion ofa self-priming pump according to a first embodiment of the presentinvention.

[0021]FIG. 2 is a sectional side view showing a casing of theself-priming pump.

[0022]FIG. 3 is a sectional view taken along a line A-A in FIG. 2.

[0023]FIG. 4 is a sectional view taken along a line B-B in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] An embodiment of the present invention will be explained indetail with reference to the drawings. A concrete structure of theinvention is not limited to this embodiment.

[0025]FIG. 1 is an axial sectional view showing an essential portion ofa self-priming pump according to a first embodiment of the presentinvention, FIG. 2 is a sectional side view showing a casing of theself-priming pump, FIG. 3 is a sectional view taken along a line A-A inFIG. 2, and FIG. 4 is a sectional view taken along a line B-B in FIG. 1.

[0026] In the drawings, a reference number 1 represents a casing, and animpeller 2 is accommodated in the casing 1. A large scroll casing 10 anda small scroll casing 11 are formed around the impeller 2. A main line12 extends from the large scroll casing 10, and a spout 13 is formed onan upper end of the main line 12. An auxiliary line 14 extends from thesmall scroll casing 11, and an upper end of the auxiliary line 14 isspirally brought into communication with the main line 12 along a wallsurface of the main line 12 from a tangent direction thereof.

[0027] A swirl flow forming space 15 is formed in the main line 12. Inthe swirl flow forming space 15, self-primed water accumulated in thecasing 1 is discharged into the main line 12 together with air from thesmall scroll casing 11 through the auxiliary line 14 during self-primingoperation, thereby generating swirl flow in the main line 12, andair-water separation is carried out. As shown in FIG. 3, a plate member16 extends in an extension direction of the main line 12 below the swirlflow forming space 15.

[0028] A suction opening 17 is formed on a central portion of one sideof the casing 1. A water tank 4 for self-primed water is providedbetween the suction opening 17 and a suction pipe 3.

[0029] As shown in FIG. 4, the water tank 4 comprises a reservingportion 40 swelling in the lateral direction and having across-sectional area greater than an opening area of the suction opening17, a water outlet 41 which laterally opens into a bottom end of thereserving portion 40 and which is in communication with the suctionopening 17 substantially horizontally, and a water inlet 42 whichlaterally opens into an upper end of the reserving portion 40 and whichis in communication with the suction pipe 3. In this case, a lower endlevel L1 of the water inlet 42 is formed higher than an upper end levelL2 of the water outlet 41 so that water is accumulated up to the lowerend level L1 of the water inlet 42 so that the casing 1 is filled withself-primed water.

[0030] An impeller shaft 20 is supported at a central portion of theother side of the casing 1, and the impeller shaft 20 is connected to adriving motor (not shown).

[0031] In the self-priming pump, circulation flow is generated in such amanner that self-primed liquid interflows into the main line 12 from thesmall scroll casing 11 through the auxiliary line 14 during theself-priming operation, the self-primed liquid returns into the largescroll casing 10 from the main line 12 and again flows into theauxiliary line 14 from the small scroll casing 11. During that time,swirl flow is generated in the swirl flow forming space 15, andair-water separation is carried out by centrifugal separation caused bythis swirl flow.

[0032] The swirl flow tries to develop into tornado with the circulationflow, but since the self-priming pump is provided with the plate member16 below the swirl flow forming space 15, the swirl flow can beobstructed by a surface of the plate member 16, and it is possible toeliminate the swirl flow which tries to extend downward.

[0033] Further, since the plate member 16 extends in the extensiondirection of the main line 12, the plate member 16 does not hinder thewater flow during the pumping operation. Only a cross-sectional areacorresponding to a plate thickness of the plate member 16 is variedbetween a portion where the plate member 16 is provided and a portionwhere the plate member 16 is terminated (swirl flow forming space 15)and therefore, water flow is not disturbed, and pumping performance doesnot become unstable.

[0034] In the self-priming pump, since air is discharged from a suctionpipe 3 while circulating the self-primed liquid in the casing 1, it isnecessary to accumulate the self-primed liquid in the casing 1 withoutfail.

[0035] Thereupon, in this self-priming pump, the reserving portion 40 ofthe water tank 4 is allowed to swell in the lateral direction. Necessaryself-primed liquid can be accumulated only by this reserving portion 40and thus, it is possible to reliably accumulate the self-primed liquidin the casing 1 when the pump is stopped.

[0036] Since it is possible to reliably accumulate the necessaryself-primed liquid only by the reserving portion 40 , the entire lengthof the pump need not be increased, and it is unnecessary to largely seta vertical level difference between the inflow port (water outlet 41)and the outflow port (water inlet 42). Therefore, the suction sidestructure can be made compact, and a pumping load can be reduced.

[0037] The water tank 4 and the casing 1 may be integrally molded witheach other.

[0038] INDUSTRIAL AVAILABILITY

[0039] As explained above, the self-priming pump of the presentinvention (claim 1) has an effect that it is possible to prevent a swirlflow from developing during the self-priming operation and to assure thesmooth flow of a stream of water during the pumping operation.

[0040] The self-priming pump of the invention (claim 2) has an effectthat it is possible to make the suction side structure compact, toreduce a pumping load and reducing the self-priming time withoutincreasing the pumping ability, and to reliably accumulate self-primedliquid in a casing when the pump is stopped.

1. A self-priming pump comprising a casing in which a large scrollcasing and a small scroll casing are formed around an impeller, a mainline extends from said large scroll casing, and a spout is formed on anupper end of said main line, an auxiliary line extends from said smallscroll casing, and an upper end of said auxiliary line is spirallybrought into communication with said main line along a wall surface ofsaid main line from a tangent direction thereof, a swirl flow formingspace being formed in said main line, and in said swirl flow formingspace, self-primed water accumulated in said casing being dischargedinto said main line together with air from said small scroll casingthrough said auxiliary line during self-priming operation, therebygenerating swirl flow in said main line, and air-water separation beingcarried out, wherein a plate member for eliminating the swirl flowextends in an extension direction of said main line in said main linebelow said swirl flow forming space.
 2. A self-priming pump wherein awater tank for self-primed water is provided between said suctionopening and a suction pipe, said water tank comprises a reservingportion swelling in the lateral direction and having a cross-sectionalarea greater than an opening area of said suction opening, a wateroutlet which laterally opens into a bottom end of said reserving portionand which is in communication with said suction opening substantiallyhorizontally, and a water inlet which laterally opens into an upper endof said reserving portion and which is in communication with saidsuction pipe, and a lower end level of said water inlet is formed higherthan an upper end level of said water outlet.